use warnings;
use strict;

sub dive { my $r = shift;
	$r = ref $r eq 'HASH' && exists $$r{$_} ? $$r{$_} : return for @_;
	return $r }

use Test::More;

my $h = { a => { b => { c => { d => 'e' } } } };

is dive($h, qw/ a         /), $h->{a};
is dive($h, qw/ a b       /), $h->{a}{b};
is dive($h, qw/ a b c     /), $h->{a}{b}{c};
is dive($h, qw/ a b c d   /), 'e';
is dive($h, qw/ a b c d e /), undef;
is dive($h, qw/ a x       /), undef;
is dive($h, qw/ a b x     /), undef;
is dive($h, qw/ a x y     /), undef;
is dive($h, qw/ a b x y   /), undef;
is dive($h, qw/ x         /), undef;
is dive($h, qw/ x y       /), undef;
is dive($h, qw/ x y z     /), undef;

is_deeply $h, { a => { b => { c => { d => 'e' } } } };

done_testing;